Cable scoring tool for stripping the covering from a coaxial cable



July 11. 1967 .1. M. MAHONEY 3,330,036 CABLE SCORING TOOL FOR STRIPPINGTHE COVERING FROM A COAXIAL CABLE Filed Jan. 5, 1966 FIG 5 3 .20 5 22United States Patent 3,336,036 CABLE SCOREN'G TOGL FCIR STREPPHNG THECOVERING FRDM A COAXIAL CABLE J. Marves Mahoney, New York, N.Y. (2269Keller Lane, Salt Lake City, Utah 84169) Filed Jan. 5, 1966, Ser. No.518,810 4 Claims. (Cl. 30-901) The present invention relates to a handoperated device adapted for use by various types of servicemen andmanufacturers for removing the insulation and shielding on coaxialcables or the like in a selected series of steps. In cable Work, it isimportant that the outer ends of the cables be stripped of insulationand shielding covering in a uniform fashion prior to making connectionwith other components but the stripping must be done without injury tothe inner conductor and, usually, its adjacent insulating covering.

In the electronics industry, coaxial cables are used very widely. Theseare shielded wire cables. They possess many advantages overstranded-type cables having only fabric or insulating material as acovering. It is of great importance that the stripping of the jacket andshielding braid should be carried out with high precision and that thesevered parts shall be properly and adequately selected in order thatdamage to the cable as a whole may not arise.

In the past, many types of devices have been proposed to achieve thisresult but, generally speaking, the prior art devices are difficult touse, they are expensive and, very frequently, require unusual type ofclamping elements in order to use them. Further than this, many of theprior art devices include more than a single unit adapted for scoring orsevering the insulation. These separate units operate without anyadequate control and are difiicult to maintain in relative adjustment sothat the cutting or scoring may readily be restricted to that particularportion of the cable covering which it is desired to strip.

The device with which this invention is concerned comprises essentially-a hand operated component which serves to strip the shielded cablewire, thereby to remove its outer jacket as well as the inner shield ina two-stage operation. The stripping unit usually comprises an outerbarrel furnished with a wire collet and a center tubular section. Withthis, a cutting or scoring unit is provided to aid in locating the cablewithin the collet and also, when used with the positioned cable, toprovide a means whereby through an oscillatory or rotary (or both)movement of the device relative to the cable, the cutting of thecovering may be achieved. As the invention is constituted, it is freefrom all of the cam-type adjustments used in the prior art and, yet, thecable is securely and firmly gripped prior to severing the covering.Through the use of the adjustable collet, as a holder, the device isusable for different cable sizes. With the cutting instrumentalityprovided as a separate component adapted to be brought adjacent to thepositioned cable, the depth of the scoring or cutting is readilycontrolled and limited.

With the foregoing thoughts borne in mind, a principal object of theinvention is to provide an insulation stripping tool readily adaptingitself to different size cables or wires and which is usable both forsevering metallic braiding surrounding a central core and held adjacentto an insulating covering and in turn, covered by an insulating coveringso that separate cuttings of the different coverings may be achieved.

Another object of the invention is that of providing a cable stripperfor removing insulation and shielding which will cleanly sever, and, inaddition, to cut any desired length of insulation and shielding that canthen be removed from the cable per se.

Further objects of the invention are those of providing a tool which issmall enough to be hand carried and which is hand operated and for whichthere is no need or requirement of multiplicity of cutting or scoringedges.

Still other objects of the invention are those of providing a cablestripping tool in which there are no dies or blades to change forditferent size cables in the use of which it is impossible to damage theinner conductor insulation by reason of limiting the action relative tothe shielding braid to that of scoring and not complete cutting, as wellas to provide a tool structure which can be operated rapidly andefficiently and by which the shield braid may be severed by workhardening strands and then, breaking them by the use of the tool itself.

The invention has been illustrated in its preferred form by theaccompanying drawings of which:

FIG. 1 is a showing of the tool in elevation;

FIG. 2 is a plan view of the structure of FIG. 1 particularly toillustrate the resilient or spring-like member used to position thecable relative to the collet and to provide the cutting edge;

FIG. 3 is an enlarged end view looking at FIG. 1 from the left for thepurpose of showing the relative position of the resilient or spring-likeguide member and the collet element;

FIG. 4 is a diagrammatic showing to. represent the relationship betweenthe coaxial cable and the blade holder and stop on the scoring member;and

FIG. 5 is an enlarged view showing the relationship established betweenthe cable, the holding collet and the resilient member with the cutteror scorer.

Considering now the drawings for a further understanding of theinvention, the tool comprises a relatively short handle member 11(generally tubular as shown by FIGS. 1 and 2). The handle is adapted tobe grasped by the operator, with the forward end 12 usually pointed awayfrom the operator to receive a cable member (not shown). The coaxialcable, as above stated, comprises, essentially, an inner conductor aboutwhich is preferably wrapped a covering of insulation and over whichthere is a braided conducting member surrounding the complete innerconductor and its insulating covering. A second insulating coveringforms an outer cover of the wire and surrounds the braided conductor.The foregoing structure is well recognized in the art as being thenormal construction of coaxial cables.

The end of the tool opposite the handle comprises a collet 14 having aknurled or ridged gripping fingers of the cylindrical portion 15 adaptedto be turned by hand to move the collet in and out along thehollowforward spindle end 16 of the tool. The collet contains the usualjaw or finger members, (see FIG. 5) which are brought together bytightening, and released by loosening, where the portion 15 is turned,as is well known. The inner end of the handle member 11 is formed into acollar portion 18, or the collar portion is secured to the handle in anydesired manner. A fiat spring-like element 20 is firmly attached at oneend 22 to the collar end 18 of the handle. The flat spring-like memberextends generally parallel to the body of the tool from the fasteningpoint on the handle to a region just slightly beyond the forward end ofthe collet 14. At the forward end, the spring member is bent inwardly,as shown at 24, until its inner end overlaps the collet opening. Theinwardly turned end 24 of the spring member has a central aperture 26which may be aligned with the collet opening by depressing the fiatspring member 20 to bring it closely adjacent to the knurled or ribbedhand portion for turning the collet.

With the spring member so positioned and its aperture 26 substantiallyaligned with the opening in the collet, the shielded coaxial cablesection may be inserted through the aperture 26 and the collet openingof the selected size. On the'inwardly extending part 24 of the flatspring member 20 a notch 30 of generally V-shape is cut to assist inremoving the insulation from the wire after appropriate scoring has beendone.

In the use of the device, the tool is grasped by the handle portion 11with the collet opening pointing outwardly. At this time, the fiatspring 20 is depressed until the aperture 26 aligns itself and indexeswith the collet opening The cable to be stripped is then insertedthrough the aperture 26 and into the collet 14 with the collet thenturned to adjust it to fit loosely around it. The flat spring 20 is thenreleased and the tool is grasped about its handle end 11 only androtated around the cable which is then held in the opposite hand of theworker from that in which the handle portion 11 is held so that the toolmay be rotated through three or four revolutions. The cutting edge 32,which is exposed for a generally critical short distance,

extends inwardly from the lower edge of the aperture 26. in such amanner that it may score the insulation about the cable. Normally, thecutting edge is formed as a sharp blade element and for the average sizecable, the blade extends about 0.0l5 inch inwardly from the outer edgeof the aperture. 7

With the scoring having been made by turning the tool about the cablepositioned generally loosely in the collet 14, the next operational stepis to tighten the collet collar 14 tightly upon the cable and then torotate the tool through an angle of approximately 90 each way from thecenter axis so that three or four substantially halfturns are made.Following this, the collet 14 is loosened, the flat spring 20 isdepressed and the cable is removed both from the tool and from passagethrough the aperture in the inwardly turned section 24 of the flatspring. With the removal of the cable from the tool, the cable is placedwith the separating scar in the groove or notch 30 formed in theinwardly extending portion of'the fiat spring member. A strong pull onthe cable, following location over the notch and maintenance of theposition by the thumb of the user, will pull the cable away from thetool until the outer jacket and mesh shield are removed leaving theinner insulating covering completely intact.

. The coaxial conductor is shown generally in section in FIG. 4 with therelationship of the cutting element or scoring blade depicted and theparticular form of the cable for which this tool is designd 'is depictedby FIG. 4. FIG. 5 shows the relationship of the conductor, thesupporting collet and the relationship of the resilient holder andcutter. The inner conductor 41 of most shielded wire is stranded to makeit more flexible, although it need not necessarily be so. The innerconductor of either type is wrapped by the insulating covering 42 overwhich there is the shielding braid 43. External to the sheilding braid,and forming the outside wrapping of the complete conductor, there isanouter insulating covering 44. In the cutting operation, the cuttingblade 32 is supported at one end of the aperture in the downwardlyturned section of the resilient member 20 where it is supported by aloop section 46 rolled over adjacent to the downwardly turned member.The blade holder thus formed stops the blade at'the proper depth byscoring blade cuts through the outer insulation and scores the shieldbraid as depicted.

The end of the resilient member, the collet and the securernent of theresilient member 20 is particularly shown by FIG. 5. The structure, asdescribed by refer- 5 ence to FIGS. 1 and 2 as related to FIG. 4 lastdiscussed,

is also generally depicted. The jaws 46 of the collet are adapted toclose over the cable as the collet is turned upon the threaded end 48are also clearly shown;

Various modifications of the foregoing structure are contemplated andmay be made within reasonable skill in the art. Therefore, the inventionis to be interpreted broadly except as limitations may be necessitatedby reaa generally fiat resilient member secured to the body 1 member,between its ends, and extending substantially parallel and adjacent tothe said body member in the direction of the open end thereof and thecollet held thereby to overlap the open end of the collet,

said resilient member having a downwardly extending end overlapping thecable-receiving opening in the collet,

said downwardly extending end having an opening therein through whichthe cable is adapted to be passed for insertion into the collet,

' the downwardly extending end of said resilient member having anopeningwhich when the said member is depressed against the body memberis adapted to be substantially aligned with the opening in the collet sothat with movement of the resilient member the cable may be insertedinto the collet, V

a cutting edge supported on at least one side of the opening in thedownwardly turned resilient member,

means to turn the device relative to the supported cable to score thecable covering, and

meansto tighten the collet upon the body member following scoring firmlyto secure a selected length of cable therein so that with furtherlimited rotation of the resilient member about the gripped cable' thecable covering may be scored for separation.

50 2. The device claimed in claim 1 wherein the downwardly dependingresilient member is notched for receiving the scored outer coveringofthe cable whereby the covering may be removed with pull upon the locatedcable;

3. A device for stripping covering from a coaxial cable having inner andouter insulation separated by a braided metallic conductor comprising,in combination,

an elongated body member,

a flat spring member secured to the body member and extending generallyparallel to the body memberto 6O overlap one of its ends said fiatspring element having an inwardly turned lip at its end overlapping theopening within the in--'' body member'and having an wardly turned lip,

the opening being of a size sufiicient to pass the end of a coaxialcable therethrough,

said body member having a substantially centrally positioned openingextending inwardly longitudinally thereof from the end adjacent to theinwardly turned lip of the flat spring member,.a rotatable collet on lyturned lip of the flat spring member, said collet 7 the spring element,

the end of the body member adjacent to the inwardsaid spring memberbeing adapted to be depressed in the direction of the axis of the bodymember whereby the openings in the depending lip and the collet may besubstantially aligned for the insertion therethrough of a cable whoseend covering is to be severed,

and a cutting element supported on the inwardly turned lip for scoringand cutting insulation on a gripped cable.

4. The device claimed in claim 3 wherein a cutting member on theinwardly extending lip is adjacent to the opening and on the side of theopening remote from the flat spring member whereby rotation of the flatspring member relative to the body member relative to a cable positionedwithin the opening into the body member is adapted to score the cablecovering for severing the same.

References Cited UNITED STATES PATENTS 3,161,088 12/1964 Tolman 819.53,204,495 9/1965 Matthews 81-9.5

WILLIAM FELDMAN, Pnz'mary Examiner. M. MEHR, Examiner.

1. A DEVICE FOR STRIPPING THE ENDS OF COAXIAL CABLES COMPRISING, INCOMBINATION, AN ELONGATED BODY MEMBER HAVING A HANDLE AT ONE END, ACABLE-RECEIVING MEMBER HAVING A GENERALLY CENTRALLY POSITIONEDCABLE-RECEIVING OPENING LOCATED AT SUBSTANTIALLY THE OPPOSITE, END, ACOLLET SECURED TO THE OPEN END OF THE BODY MEMBER FOR TIGHTENING, WITHROTATION, ABOUT A CABLE END ADAPTED TO BE INSERTED THEREIN, A GENERALLYFLAT RESILIENT MEMBER SECURED TO THE BODY MEMBER, BETWEEN ITS ENDS, ANDEXTENDING SUBSTANTIALLY PARALLEL AND ADJACENT TO THE SAID BODY MEMBER INTHE DIRECTION OF THE OPEN END THEREOF AND THE COLLET HELD THEREBY TOOVERLAP THE OPEN END OF THE COLLET, SAID RESILIENT MEMBER HAVING ADOWNWARDLY EXTENDING END OVERLAPPING THE CABLE-RECEIVING OPENING IN THECOLLET, SAID DOWNWARDLY EXTENDING END HAVING AN OPENING THEREIN THROUGHWHICH THE CABLE IS ADAPTED TO BE PASSED FOR INSERTION INTO THE COLLET,THE DOWNWARDLY EXTENDING END OF SAID RESILIENT MEMBER HAVING AN OPENINGWHICH WHEN THE SAID MEMBER IS DEPRESSED AGAINST THE BODY MEMBER ISADAPTED TO BE SUBSTANTIALLY ALIGNED WITH THE OPENING IN THE COLLET SOTHAT WITH MOVEMENT OF THE RESILIENT MEMBER THE CABLE MAY BE INSERTEDINTO THE COLLET, A CUTTING EDGE SUPPORTED ON AT LEAST ONE SIDE OF THEOPENING IN THE DOWNWARDLY TURNED RESILIENT MEMBER, MEANS TO TURN THEDEVICE RELATIVE TO THE SUPPORTED CABLE TO SCORE THE CABLE COVERING, ANDMEANS TO TIGHTEN THE COLLET UPON THE BODY MEMBER FOLLOWING SCORINGFIRMLY TO SECURE A SELECTED LENGTH OF CABLE THEREIN SO THAT WITH FURTHERLIMITED ROTATION OF THE RESILIENT MEMBER ABOUT THE GRIPPED CABLE THECABLE COVERING MAY BE SCORED FOR SEPARATION.